.travis.yml: Install libxml-parser-perl
.travis.yml: Install libxml-parser-perl

Fix error: Unsatisfied dependency: XML::Parser
Homebrew does not provide Perl dependencies; install with:
  cpan -i XML::Parser

LinuxbrewTestBot/homebrew-core,forevergenin/homebrew-core,Linuxbrew/homebrew-core,maxim-belkin/homebrew-core,rwhogg/homebrew-core,forevergenin/homebrew-core,rwhogg/homebrew-core,LinuxbrewTestBot/homebrew-core,Linuxbrew/homebrew-core,maxim-belkin/homebrew-core